Mechanism for converting rotary motion into approximately hypocycloidal motion



Sept. 21, 1948. F. A. SNELL 2,449,958

MECHANISM FOR CONVERTING ROTARY MOTION INTO APPROXIMATELY HYPOCYCLOIDAL MOTIQN Filed March 19, 1946 Inventor Patented Sept. 21, 1948 UNITED STATES PATENT-OFFICE MECHANISM FOR CONVERTING ROTARY MOTION INTO APPROXIMATELY HYPO- CYOLOIDAL MOTION' Francis A. Snell, Chenango Forks, N. Y.

Application March 19, 1946, Serial No. 655,408

I 3 Claims. (01. 74 '112 This invention relates to mechanism for producing intermittent rotary motion and, more particularly, to mechanism in which the path of the moving element is similar to a hypocycloid.

The principal object of this invention is to provide means whereby continuous rotation of a driving member may be converted into intermittent rotary motion of a driven member.

A more particular object of this invention is to provide means whereby continuous rotary motion may be converted into an intermittent Withdrawing and advancing'motion in a circular path which may be described as approximately hypocycloidal motion.

Another object of this invention is to provide a mechanism which will produce a motion useful for the actuation of certain types of electrical switches, toys, and the like.

A further object of the invention is to provide a construction which is simple and rugged, easy to manufacture, and has few moving parts.

One form of my invention is illustrated in the accompanying drawing, in which Fig. 1 is an isometric view of the mechanism, with the moving parts shown in one position, and Fig. 2 is a plan view of the same, with the moving parts shown in other positions to disclose the operation of the device.

On a base I, is a rotatable shaft 2, to which is aflixed an eccentric 3. Eccentric 3 actuates an eccentric strap 5, from which project a contactor 4, and a fork 6. The contactor includes a spring member 1, which allows the contactor to shorten when longitudinal pressure is exerted upon it. The contactor also has a semicircular notch at its free end.

Arranged in circular arcs about shaft 2, are contact pins 8 and guide pins 9, I I], ll, etc. In the construction illustrated, guide pins 9, III, II, etc., are made short enough so that contactor 4 can pass over them when necessary.

Operation ward guide pin [0, as shown by the solid lines in Fig. 2. As the eccentric is rotated still further in the same direction, fork 6 will descend and straddle guide pin l0, bringing the parts into the same respective positions shown in Fig. 1,

the right.

2 but with the eccentric rota'ted approximately Further. rotation of the eccentric will cause contactor 4 to Withdraw from engagement with the contact pin shown in Fig. 1, and swing over, ready to engage the next contact pin to This phase of the movement (but not the identical position) is shown by the dotted lines in Fig. 2.

. In this manner, contactor 4 advances from one contact pin to the next for each revolution of shaft 2; the direction of the rotation of eccentric strap 5, with its attached parts, being opposite to the direction of rotation of shaft 2.

By properly proportioning the various parts of the mechanism and the throw of the eccentric, the angular spacing of the contact pins and the guide pins can be made such that the ratio 15 being the throw of the eccentric, 1' being the radius of the guide pin circle, and R. being the radius of the contact pin circle. tinuous rotation, 15, r, and R must be so chosen that will be an integer.

From these relationships it will be seen that it is possible to dispense with the guide pins, if desired, and, by constructing fork 6 so that it will engage the contact pins in a manner similar to contactor 4, the device will operate with a circle of contact pins only. For this special condition r=R and the angular spacing is 4 times the angle whose sine is It is also to be noted for this special case that the contact elements 4 and 6 will not be dia- Then, for con metrically opposite but will be out of line with one another by one half the angular spacing.

The construction herein shown and described is only one embodiment, and various modifications might be made without departing from the spirit of the invention. Accordingly, I wish it to be understood that such modifications are included within the scope of the invention and, specifically, that other types of springs may be used in place of spring I, that contact pins-8 may be replaced by other guiding elements such as holes or notches designed to receive the free end of contactor 4, that any suitable frame or housing may be substituted for base I, and that -a crank is to be understood as a full equivalent and substitute for an eccentric wherever the latter is mentioned in this specification, :or the following claims.

What I claim is:

P1. In a device of the character described, the H 30 Number and oppositely disposed extensions thereof, and guide means arranged at intervals in circular configuration about said eccentric and adapted to engage alternately the extended portions of the driven member when it is oscillated by the rotation of the eccentric and to advance said driven member one interval for each revolution of the eccentric.

3. In a device of the character described, the combination of a base, an eccentric rotatable relative to said base, a member driven by the eccentric comprising an eccentric strap and oppositely disposed extensions thereof, one extension having the form of a fork and the other 5 extension comprising a longitudinally compressible rod, and a plurality of guide means disposed at equal angular intervals in circular configuration about the eccentric and adapted to engage the extremities of the driven member in alternation and to advance said member one of said angular intervals :for each revolution of sthe veccentric.

FRANCIS A. REFERENCES CITED The following references are -of record vin ithfi file of this patent:

FOREIGN PATIENTS Country Date 387,7 33 Germany. Jan. 4, 1924 

